Louis de Broglie If light, which we thought of as a wave, behaves as a particle, then maybe things we think of as particles behave as waves… photo from.

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Presentation on theme: "Louis de Broglie If light, which we thought of as a wave, behaves as a particle, then maybe things we think of as particles behave as waves… photo from."— Presentation transcript:

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Louis de Broglie If light, which we thought of as a wave, behaves as a particle, then maybe things we think of as particles behave as waves… photo from http://www.aip.org/history/heisenberg/p08.htm

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Energy/Frequency and Momentum/Wavelength Relations for a Photon Energy/Frequency and Momentum/Wavelength Relations for an Electron/Proton/Apple Pie/Ford Taurus

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What Exactly is Waving? For a photon... For a photon... –electric and magnetic fields –You can measure them if f is small enough. –For visible light, you can see that it is a wave indirectly. For a massive particle For a massive particle –You can’t measure them --- even in theory! –They are complex! –How do we know that there’s really a wave?

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Thought Question Which of the following would be the easiest particle to use if I wanted to see a matter- wave diffraction pattern? A.A car moving at 100 mph B.A car moving at 1 mph C.A 1 MeV electron D.A 10 eV electron E.What was the question?

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C 60 Interference Interference fringes! The interfering particle: Buckyballs Apparatus http://www.quantum.univie.ac.at/ Recent results from Vienna group of Anton Zielinger: Not only more mass, but more degrees of freedom too!

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Wave-Particle Duality Things act as wave when propagating Things act as wave when propagating –or, in other words, we use waves to make predictions as to what we will find when we make our measurement. Things act as waves when we measure wave- like properties. Things act as waves when we measure wave- like properties. Things act as particles when we measure particle-like properties Things act as particles when we measure particle-like properties Example: BEC interference --- theorists confused about “undefined phase” Example: BEC interference --- theorists confused about “undefined phase”

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WHERE CAN YOU FIND TRUTH? A ride with a tow truck driver A ride with a tow truck driver An article on idiots filled with... the word An article on idiots filled with... the word Peer reviewers trying to sound smart Peer reviewers trying to sound smart A Buddhist Sunday school teacher A Buddhist Sunday school teacher

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WHERE CAN YOU FIND TRUTH? "We believe in all truth, no matter to what subject it may refer. No sect or religious denomination [or, I may say, no searcher of truth] in the world possesses a single principle of truth that we do not accept or that we will reject. We are willing to receive all truth, from whatever source it may come; for truth will stand, truth will endure." -- Joseph F. Smith

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Bohr Theory Successes/Failures ☺ Predicts emission and absorption lines of hydrogen and hydrogen-like ions ☺ Predicts x-ray emissions (Moseley’s law) ☺ Gives an intuitive picture of what goes on in an atom ☺ The correspondence principle is obeyed... sort of X It can’t easily be extended to more complicated atoms X No prediction of rates, linewidths, or line strengths X Fine structure (and hyperfine structure) not accounted for X How do atoms form molecules/solids? X Where did it come from? There must be a more general underlying theory! ☺ It gave hints of a new, underlying theory

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Schorodinger’s Idea Probability waves Probability waves –Tells the probability of finding a particle at some particular place at a particular time. –The electron is more likely to be where the amplitude of the wave is high.

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Match the spectrum to the one you see. HHeONe http://jersey.uoregon.edu/vlab/elements/Elements.html http://www.colorado.edu/physics/2000/quantumzone/index.html http://astro.u-strasbg.fr/~koppen/discharge/

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Postulates of Quantum Mechanics Every physically-realizable system is described by a state function ψ that contains all accessible physical information about the system in that state Every physically-realizable system is described by a state function ψ that contains all accessible physical information about the system in that state The probability of finding a system within the volume dv at time t is equal to |ψ| 2 dv The probability of finding a system within the volume dv at time t is equal to |ψ| 2 dv Every observable is represented by an operator which is used to obtain information about the observable from the state function Every observable is represented by an operator which is used to obtain information about the observable from the state function The time evolution of a state function is determined by Schrödinger’s Equation The time evolution of a state function is determined by Schrödinger’s Equation